Our goal is to measure frequencies of point mutations in sperm from mice treated with mutagens. Our strategy for detecting mutations is based on immunologic differences in a sperm-associated isoenzyme, lactate dehydrogenase-X (LDH-X) existing as isomeric forms immunologically identifiable to each species (i.e., mouse, rat, humans). Dr. Ansari previously reported that normal antibody to rat LDH-X does not react with LDH-X associated with mouse sperm; however, low frequencies of mouse sperm contain LDH-X that reacts with antibody in rat LDH-X. Moreover, mice treated with the mutagen procarbazine generate increased frequencies of mouse sperm that react with antibody to rat-form LDH-X. The increased frequency of sperm expressing rat-form LDH-X increases linearly with increasing doses of procarbazine. We will develop monoclonal antibodies.